code: def test_stieltjes():
      assert isinstance(stieltjes(x), stieltjes)
      assert isinstance(stieltjes(x, a), stieltjes)
  
      # Zero'th constant EulerGamma
      assert stieltjes(0) == S.EulerGamma
      assert stieltjes(0, 1) == S.EulerGamma
  
      # Not defined
      assert stieltjes(nan) is nan
      assert stieltjes(0, nan) is nan
      assert stieltjes(-1) is S.ComplexInfinity
      assert stieltjes(1.5) is S.ComplexInfinity
      assert stieltjes(z, 0) is S.ComplexInfinity
      assert stieltjes(z, -1) is S.ComplexInfinity
  
imports: from sympy.concrete.summations import Sum
  from sympy.core.function import expand_func
  from sympy.core.numbers import Float, I, Rational, nan, oo, pi, zoo
  from sympy.core.singleton import S
  from sympy.core.symbol import Symbol
  from sympy.functions.elementary.complexes import Abs, polar_lift
  from sympy.functions.elementary.exponential import exp, exp_polar, log
  from sympy.functions.elementary.miscellaneous import sqrt
  from sympy.functions.special.zeta_functions import dirichlet_eta, lerchphi, polylog, riemann_xi, stieltjes, zeta
  from sympy.series.order import O
  from sympy.core.function import ArgumentIndexError
  from sympy.functions.combinatorial.numbers import bernoulli, factorial, genocchi, harmonic
  from sympy.testing.pytest import raises
  from sympy.core.random import test_derivative_numerically, random_complex_number, verify_numerically
label_desc: Use image node_id 13 for calling a global function with example usage: test_stieltjes() without return types